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Summaries of Research Using Stored Specimens

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Many participants agreed to the collection and storage of their blood and urine for future studies. Many tests used these blood or urine samples to advance science. The following are summaries of the research that has used the specimens collected for survey years 1999-2006:

1999-2000

Characterization of Levels of Contemporary Pesticides, Perfluorochemicales and Brominated Flame Retardants in the US Population.

This study looked at polyfluoroalkyl chemicals (PFCs) that are used in many industrial and consumer products such as protective coatings for fabrics and carpet, paper coatings, insecticide formulations and surfactants. The potential health risk for exposure is unclear. This study used pooled serum and found patterns of human exposure to PFCs differ among demographic groups in the U.S.

Aflatoxins are toxic products of molds that commonly grow on food (Aspergillus flavus, Aspergillus parasticus, Aspergillus nominus, Aspergillus niger). Under the right conditions Aspergillus can grow on corn, animal feed, rice, peanuts, tree nuts, dried fruits, dried herbs and spices, tobacco and other foods. Under drought conditions, plants are more susceptible to insect damage, and insects are the primary way the mold gets carried to the corn, fruits, seeds and nuts. Thus, aflotoxins commonly contaminate crops grown during periods of drought. These scientists looked to see if individuals had detectable levels of aflotoxin during 1999 the year following a drought in Midwestern US. Preliminary data show that few NHANES 1999-2000 participants had aflotoxin exposure that could be measured.

Herpes simplex type 1 (HSV-1) among US Youth: Seroprevalence and test performance for pediatric and adolescent sera based on stored sera from the National Health and Nutrition Examination Surveys (NHANES) 1999-2000 and 2001-2002.

HSV-1 is a common infection in U.S. children (31% in children aged 6-13 years). The proportion of children infected with HSV-1 increased with age, from 26% in 6-7 years olds to 36% in 12-13 years olds. The proportion infected with HSV-1 was similar in boys and girls but varied by race/ethnicity, birthplace and poverty level. The proportion of children infected with HSV-1 was 25% among non-Hispanic whites, 48% among non-Hispanic blacks, and 42% among Mexican Americans.

1999-2004

Immunity to Mumps

Antibody to mumps was measured in participants age 6-49 years to determine how many had antibody. Antibody is produced in response to natural infection or a vaccine. Ninety present of the NHANES population had mumps antibody. This reflects the lower end of the estimated population immunity (90-92%) needed to achieve mumps elimination in the United States.

Immunity to Varicella-zoster virus (Chicken pox)

Antibody to varicella zoster virus (chicken pox) was measured to determine if immunity to chicken pox has been maintained since the chicken pox vaccine has been used in the United States. Data from this study show that the vaccination program has maintained immunity among children aged 6-19 years.

Cytomegalovirus prevalence in the United States

Congenital cytomegalovirus is the most common congenital infection in the U.S. resulting in permanent disabilities such as mental retardation, vision loss, and hearing impairment for more than 5,500 children per year. This study looked at the burden of infection among individuals age 6 to 49 years and found 50.4% were previously infected. Infection prevalence differed by race/ethnicity gender and socioeconomic status.

2001-2002

Measurement of perchlorate exposure in the NHANES 2001-2002 population

Perchlorate can disrupt thyroid function by competitively inhibiting iodine uptake Perchlorate is a chemical that can disrupt thyroid function by interfering with iodine uptake. Measurement of perchlorate, nitrate and thiocyanate in stored urine samples from NHANES 2001-2002 enabled the researchers to characterize the magnitude and distribution of exposure in the U.S. population . Researchers found that perchlorate exposure was more widespread than expected, and that children had higher exposure than did adults. In addition, perchlorate exposure was linked with changes in thyroid hormone levels in women with urinary iodine less than 100 µg/L. Perchlorate exposure is most tightly linked with thyroid hormone levels in cigarette smokers.

2003-2004

Racial/ethnic variation in sex hormone concentrations by age in men

The objective of this study was to compare serum testosterone, estradiol and other hormones in the NHANES male population. The results of the study demonstrated that there was not racial difference in testosterone levels between black and white men. Mexican American men have higher testosterone than whites but similar estradiol. Because of these findings the researchers felt it may be equally important to look at estradiol as testosterone in relation to diseases in men.

Q fever is a disease that comes from contact with infected cattle sheep and goats. People develop flu-like symptoms with some people developing more sever infection or even chronic infection. This study is the first study to determine the overall extent of infection in the US. Overall prevalence was 3.1% in adults age 20 or more years. Prevalence was higher for men (3.8%) then for women (2.5%) Mexican Americans had higher prevalence of infection (7.4%) compared to whites (2.8%) and blacks (1.3%). These findings indicate that national prevalence of Q fever in the U.S. is higher than expected based on the number of cases reported to the Centers for Disease Control and Prevention from state health departments.

Measurement of Cystatin C in the U.S. population

Cystatin C is a marker of kidney function. It is used to accurately estimate kidney function in the population. The addition of this measure to the other laboratory variables collected in NHANES was used to develop new equations to estimate kidney function and to estimate the utility of the cystatin C lab test in clinical practice.